The present invention relates to a tire pressure indicator and, in particular, to such an indicator in combination with a tire stem valve.
For the maintaining of tire vehicles at a pressure which provides economical vehicle operation and satisfactory vehicle ride quality, it is desirable to determine the need for tire pressure adjustment when such need arises. Commonly, a tire pressure gauge is manually applied to each tire valve stem to provide a measure of tire pressure. It has also been proposed to provide various, structures permanently mounted either in the tire, in combination with the valve stem, or separately therefrom, for the providing of an indication of tire overpressure or of underpressure, as the case may be.
It has been found that overinflation is a common problem at service station air pumps. When fully inflated my valve will lock and at no time can you overinflate the tire.
Pressure measuring structures can be very useful, and, as such, it is a general concern of this invention to make improvements in such structures to enhance the reliability and readability of indicators which are combined with a tire stem and which address problems of tire underpressure (causing wear of the outer tire edges and the generation of heat) and tire overpressure (which causes excessive wear in the center groove area and renders the tire more susceptible to damage from objects on the road). Wheel axis mis-alignment also results from unequal pressures in the respective tires.
The present invention is also concerned with tire pressure compensation means, such as in the use of an integrated pressurized fluid capsule, in association with the basic structure of the invention. This feature addresses the prblem of tire pressure compensation due both to tire rotation and unexpected tire deflation.
The prior art, as is known to the inventor, is best reflected in U.S. Pat. No. 3,670,688 (1972) to Seaberg, entitled Composite Valve Stem; U.S. Pat. No. 4,3310,014 (1982) to Parker, entitled Tire Pressure indicator integral with Tire System; U.S. Pat. No. 4,557,308 (1985) to Kuypres, entitled Tire Valve and Low Pressure Indicator. The structures reflected in said patents and in other part, do not provide the simplicity of operation and as economy viability that is reflected in my invention as set forth below.